A pump including a rotor comprising a motor portion, first and second axial extensions having different diameters extending therefrom, a stator comprising a stator housing having a rotor chamber for receiving at least the axial extensions therein, and first and second seals mounted around the first and second axial extensions, the axial extensions being provided with liquid supply channels cooperating with the respective first and second seals to create first and second valves that open and close liquid communication across the respective seal as a function of at least the angular displacement of the rotor. The pump module comprises a third seal mounted around the second axial extension proximate the motor portion of the rotor, delimiting an outlet portion of the rotor chamber.